Last year, economists at universities in Colorado, Oregon, and Montana concluded there is no statistical evidence that marijuana legalization increases the likelihood of teen use. In fact, they found that teen use often went down in states after they liberalized their marijuana laws.

A federal survey conducted by the U.S. Centers for Disease Control and Prevention shows teen marijuana use remained virtually unchanged in Rhode Island from 2009 to 2011 as the state implemented its medical marijuana program. In Colorado, it decreased 11 percent after legislators approved a system of regulated medical marijuana sales and hundreds of storefront marijuana businesses began popping up throughout the state.

If our goal is to control teen marijuana use, we must begin by actually controlling marijuana -- something Rhode Island's prohibition laws have utterly failed to do. By regulating marijuana like alcohol, the state could take sales out of the underground market so that authorities know who is producing it, who is selling it, where, when, and most importantly, to whom.

Robert J. Capecchi
Washington

The writer is deputy director of state policies at the Marijuana Policy Project.